diff --git a/fun.go b/fun.go
index 2983fd4..cb9a805 100644
--- a/fun.go
+++ b/fun.go
@@ -256,7 +256,7 @@ func xfiltrate() string {
 	return xcelerate(b[:])
 }
 
-var re_hashes = regexp.MustCompile(`(?:^| )#[[:alnum:]][[:alnum:]_-]*`)
+var re_hashes = regexp.MustCompile(`(?:^| )#[[:alnum:]]*[[:alpha:]][[:alnum:]_-]*`)
 
 func ontologies(s string) []string {
 	m := re_hashes.FindAllString(s, -1)